Dispensing devices for discharging fluid from a supply container, particularly in a spray, are widely known in the prior art. These fluid dispensers traditionally utilize a piston and cylinder as the pump chamber and a spring to provide the piston return force. They include a means for checking the flow of fluid into and out of the pump chamber and a means for discharging the fluid, preferably in a spray. Channels are incorporated into the dispensing device housing to provide a path for the fluid to and from the pump chamber. Examples of such dispensing devices are found in U.S. Pat. Nos. 4,153,203 (Tada) and 4,819,835 (Tasaki). One drawback to such dispensing devices is the great amount of friction between the piston and the cylinder due to the telescopic fit required to maintain a fluid tight seal. This friction, in conjunction with binding of the piston in the cylinder, are sources of energy loss, thereby increasing the required overall energy to dispense the fluid and the required spring energy to return the piston. In addition, the use of the dispenser housing to provide fluid channeling results in a complex part to manufacture. This, in conjunction with the many parts that go into a fluid dispenser of this type, increases the cost of the dispenser.
U.S. Pat. Nos. 3,973,700 (Schmidt), 4,225,061 (Blake), 4,260,079 (Cary), and 4,489,861 (Saito) reveal dispensing devices that utilize a flexible pump, specifically a bellows, to replace the function of the piston, cylinder and return spring. The use of such a flexible pump is substantially free of friction and binding losses associated with the piston and cylinder. However, these dispensing devices still utilize the dispenser housing to channel the fluid. In addition, little attempt is made to reduce the total number of parts in the dispenser assembly. Therefore complexity and cost are similar to the afore mentioned piston and cylinder dispensing devices.
Still other fluid dispensing devices utilize a diaphragm or bladder as the flexible pump. Examples of such are found in U.S. Pat. Nos. 3,749,290 (Micallef), 4,155,487 (Blake), and 4,310,107 (Wesner). These devices are substantially free of friction and binding losses associated with a piston and cylinder. However, these devices also utilize the housing for channeling the fluid, thereby increasing the complexity and cost of that part.
U.S. Pat. Nos. 4,898,307 (Tiramani) and 5,114,052 (Tiramani) reveal a dispensing device that utilizes a flexible pump, specifically a bellows, wherein a fluid channel is formed from the fluid supply container to the discharge nozzle by means of a dip tube and an integrally formed bellows and discharge tube. The bellows is positioned perpendicular to the discharge orifice and in line with the dip tube and as such must have coupling means with the dispensing device's trigger lever arm so as to transfer the rotational motion of the lever arm into translational compression of the bellows. The discharge tube is required to couple the bellows portion with the discharge nozzle and is positioned in line with and adjacent to the discharge nozzle. As such, the discharge tube must be bent 90 degrees with respect to the bellows in the assembled fluid dispensing device. Although this dispensing device eliminates the fluid channeling from the device's housing, the requirement of having to couple the bellows pump with the discharge nozzle through a discharge tube which must be bent 90 degrees with respect to the bellows in assembly makes for a costly and complicated part. In addition, the discharge tube is additional pressure drop between the bellows and the discharge nozzle. Further, since the discharge tube is formed integral with the bellows, it is made of the same resilient material. Dispensing devices of this type may store flow energy within the discharge tube thereby causing the discharge nozzle to dribble or not have clean flow cutoff.
Other prior art devices simplify the fluid channel by positioning the flexible pump in line with and adjacent to the discharge orifice. Examples of such fluid dispensers, utilizing a bellows as the flexible pump, are found in U.S. Pat. Nos. 2,774,518 (Greene), 3,124,275 (Lake), and 4,732,549 (von Schuckmann). These fluid dispensers provide means for a fluid channel comprising a dip tube, a bellows pump and a nozzle actuator. However, these fluid dispensing devices require direct coupling means between the displacement motion of the nozzle actuator and the compression of the flexible pump, wherein no mechanical advantage or lever action is provided. This is a drawback when the fluid dispenser is used to discharge higher viscosity fluids or fluids in a spray where high pressure losses are present. In addition, these fluid dispensing devices have discharge orifices that move with the motion of the nozzle actuator, thereby increasing the difficulty of depositing fluid with precision.
U.S. Pat. No. 4,101,057 (LoMaglio) discloses a dispensing device that utilizes a flexible pump, specifically a bladder, wherein the bladder is positioned in line with and directly adjacent to the nozzle discharge orifice. A coupling means is provided between a trigger and the bladder so that rotational motion of the trigger lever arm results in compression of the bladder. However, in order to complete the fluid path from supply container to discharge orifice, the dispenser incorporates channeling into the housing, thereby increasing the cost and complexity of that part.